CA1097318A

CA1097318A - Lubricating method and compositions with mxy.sub.3 compounds

Info

Publication number: CA1097318A
Application number: CA301,351A
Authority: CA
Inventors: John M. Longo; John J. Steger
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1977-04-18
Filing date: 1978-04-18
Publication date: 1981-03-10
Also published as: DE2816213A1; IT7822403A0; FR2388042A1; GB1603585A; JPS54160A; FR2388042B1

Abstract

ABSTRACT OF THE DISCLOSURE
Materials of the general formula MXY3 wherein M is selected from the group consisting of Mg. V, Mn, Fe Co, Ni, Zn, Cd, Sn, Pb and mixtures thereof;
X is a pnictide selected from the group consisting of phosphorus, arsenic, antimony, and mixtures thereof, and Y is a chalcogenide selected from the group consisting of sulfur, selenium and mixtures thereof, have been discovered to be superior lubricants exhibiting resistance to oxidation and thermal degradation, low friction, excellent antiwear activity and long effective life. Metal surfaces coated with such materials resist galling and damage due to adhesive or corrosive wear. These materials can be used as dry solid lubricants or as additives to oils and greases.

Description

3~L~
It has been discovered and forms the basis o~ this disc_o-sure that materials of the formula MXY3 wherein M is selected 'rom the group consisting of Mg, V, Mn, Fe, Co, Ni, Zn, Cd, Sn, Pb and mixtures thereof, preferably Fe, Zn and mixtures thereof, most pre-ferably Zn, X is a pnictide selected from the group consisting of phosphorus, arsenic, an-timony, and mixtures thereof, preferably phosphorus, arsenic and mixtures thereof, most preferably phos-phorus and Y is a chalcogenide selected from the group consisting of sulfur, selenium, and mixtures thereof, most preferably sulfur are superior lubricants exhibiting resistance to oxidation and ther-mal degradation, low friction, excellent antiwear activity and long effective life. Surfaces coated with these compositions resist galling and damage due to adhesive or corrosive wear. As lubricants they can be used either dry or in conjunction with conventional lubricants selected from the group consisting of lubricating oils and greases.
S. Soled and A. Wold in "Crystal Growth and Characteriza-tion of In2/3 PS3", Mat. Res. Bull. Vol. 11, pg. 657-662, 1976, Pergamon Press, Inc., discuss in their introduction a number of mi~ed anion rich compounds of metal, pnictide and chalcogenides.
They report the work o~ W. Klingen, Dissertation, Universitat Hohenheim, Germany, 1969, dealing with the crystal growth of the compounds M PX3 (with M = Fe, Co, Ni, Zn, Mn, Cd, Sn, Hg or Pb; X =
S or Se) by means of chemical vapor -transport. They go on to indi-cate that these materials are structurally related to the layer compounds CdI2 and CdC12 and contain close packed sulfur layers with every other interlayer filled with an ordered arrangement of metal atoms and sigma-bonded phosphorus-phosphorus pairs. The metal atoms are located in octahedral interstices and each phosphorus atom is bonded in a distorted tetrahedron to three sulfur and one phosphorus atom. Because of the large anion-anion interlayers that remain empty (with a typical sulfur-sulfur interplanar distance of 3.4 A), these compounds exhibit easy cleavage parallel to the crystal faces and exhibit lubricity.
It was not recognized, however, that such material pos-sesses and retains this lubrication capability under oxidizing cond-itions at relatively high temperatures and performs satisfactorily over periods of time which greatly exceed the operational times of conventional lubricants such as MoS2.
In SLE Transactions, 14, 62, (1970) by Jamison and Cosgrove, the lubricating characterlstics of a number of layered transition metal disulfides and diselenides were measured. The coefficient of friction was determined using a ball on flat type test apparatus loaded to 250g force. The static wear member was a 3/~ inch steel sphere. The lubricants were hand burnished onto a brass disc which acted as the dynamic wear member.
For the layered transition metal compounds which were stu2ied, three types of lubricating behavior were observed~ Some materials did not form adherent films; others did form films but could not su~port a sliding load; yet others formed films which could support heavy sliding loads. This clearly demonstrates that not all layered materials and more particularly not all layered sulfiaes are effective as solid lubricants.

3 _ ~9~

1 ~ubrlca~:ion urlder a v~rlety of conditions, i.e.

2 oxidizing~ reducing and inert a~mosph~e a~ temperatures up

3 to abou~ 450CC, preferably from about 3lOC ~o about 450~,

4 more preferably f~^om abou~ ~00C to abou~ 450C, mos~ prefer-ably from about 21C to about 45~C~ can be ~chieved by util~-6 zing materials of ~he ormul.a ~XY39 whe~ein M is selected fi~
7 the g~oup consisting of Mg9 V, ~n~ Fe~ Co, Ni, Zn, Cd, Sn, 8 Pb and di and poly mi~ures thereo, preferably Fe~.~n and 9 mixtures thereo~, mos~ preferably ~n, X is a pnictide se o lerted from ~he group consisting of ph osphor u S9 ll arsenic, anti.mony, a n d m ix tllr e 5 ~hereof, pre~erably 12 phosphorus, arsenlc and mixtures t~ reof, most preferably phosphorus, and Y is a chalcog~nide selected from ~he group consisting o sulur, selenium and miæ~ures thereof7 mos~
15 preerably sulfur.
16 B~ using such materials, wear ean be grea~ly 17 reduced since the lubr~cant resis~s brea~down due to .a~mos-18 phe~e and tempera~ure conditlons particularly oxidation and 19 hlgh-temperature decompos;tion Consequently, these 20 materials are super~or lubrican~cs to those known ln 21 ~he art such as MoS~ which deteriora~e in oxidl~ing atmos-22 pheres at relatlvel~ low temperatures. Materials which thus 23 de~erlorate ultimately permit high ~ric~ion and damage to Z4 thé surfaces they were meant ~o protee~, the damage being 2S recogn~zed as increased wear; galling, abrasion, ~coring, ~26 coxrosion, etc.
27 The mat~rials MXY39 ~herein M~ X and Y are as ~8 previously defined1 which f~mc~ion as lubricants are prepared by any number o~ n~e~llods kno~n in the ar~. For example9 ~he lubricating materials can be pre~lared by the direc~ reac~ion 31 o the el~ments in e~acua~ed sealed silica tube re~ult:ing .. ~

~7 3~ ~ ;

1 in the ~o~mation ol polycrys~alline materials.
2 Materlals of th~ fo~mula 1~XY3 w'nerein M, X and 3 are as previously de~ined~ exhibit remarkable stability a~
4,temperatures up to 450C9 preferably 400-450~C, more preferably 3lO-450C~ most p.eferably 2l-450C9 under a variety of condi-6 tions rangi.ng from reducing to inert to oxidizing~ preferably 7 oxidizing. It is ~he .s~ability of the materials at elevated 8 temperatures under oxidiæing conditions and high load which g makes them outs~an ding lubricants.
~he ma~erlals useful in ~he instant i~v2ntion May 11 be of ~hç general formula M.~Y3 w'nerein Mg X a~d Y are as 12 previously de~ined. Fur~her~ they may be di- or poly mixed i3 catioQ or anion sol~d solu~ions~ ~ha~ is, the material may 14 lnclude more ~han one metal and/or more khan o11e chalcoge~
nide, ~or ex~ple i~ Zr~ eqPS3 O ~ q C 1 17. FePSe3WZSZ O ~ Z ~ 3 18 ZQ1 q~eqPSe3~ZSZ O -- q ~ 1 19 t) ~ ~ ~ 3 Such m~xed metal and/or mix~ed chalcoge~li.de ma~erials are 21 inc~uded within the scope of the invention~ In general, pre~
22 ferred materials are ZnPS3, FeP.S3, and PbPS3.
23 The M~3 materials can ~e added to lubricating 2L~ greases in any num~er of ways. Direct addition (suspension) 2~ of finely divided ~Y3 is one alternative, while another is 26 the susperLsion in lubricating ~ils o ~3 ma~cerials which 27 ha~e b en reduced ~c~ a fine particle size by chemlca~ or 28 mechanical means. Briefly, this last mentioned tec~miqu~ in-~9 volves di~,persing the M~Y3 material in a suitable medla such 30 as a small volume o natural or syn~het:ic oils to which has 31 been preerably added a small amcunt of a surface aCti~Je _ 5 ~

1 dispersing agent. Th-tS iS therl added to the lub~ica~ing oil 2 as an additive in suspe~sion. T~e ~rease or lubricant l~e-ria 3 resulting from the additiorl of the ~Y3 ~ype material contains ~ from .1% ~o 20 ~t. % MXY3 ~ype material~ preferably 1~5 ~. %, the balance ~eing lubri~atillg oil or grease.
6 Included are greases wherein lubricating oil is thick-7 e.ned with salts~ soapsg soap-sal~ or mixecl salt complexes, 8 p~1ymeric thickeners (e.g~ polymers o~ C2 to C4 monoolefins of g 10,000 to 200,000 Staudinger molecular weigh~ such as polyeth-3-lo lene) and inorganic ~hickeners (e.g. clay, carbon black, silica 11 gel, e~c.) However, the method of ~he ln~en~ion is o parti-12 cular value in cases w~ere the grease is thickened with a me~al 13 soap other ~han sodlum, and particularly where ~he metal is 14 polyvalent~ viz., an al~lline earth metal such as c~lcium, or 15 aluminum-16 Generally~ the greases will comprise a major amount of 17 ei~her a synthetic or natural lubrica~ing oil, thickened wi~h 18 about 3 to ~9 wt. percent~ usually 20 to 4S wt. percent, of 19 a ~hickener. In the case of soap-salt and mixed-salt thick-20 eners, ~he thickener is usually onned byco-neu~raliæation in 21 oil, by metal base, while heating ~o dehydrate or remove 22 alcohol (if an alcoholate is used in the me~al base~ of various 28 mixtures of high molecular weigh~ carboxylic acids, e.g. ~atty 2~ acids and/or inte~mediate molecular weight carboxylic acids, 25 eOg. atty or aromatic acids, with low molecular weigh~
26 carboxylic~ e.g. atty acids.
27 The high molecular weigh~ carhoxylic acids useful 28 ~or o~ming soap, soap-salt and mîxed salt thickeners include 29 na~urally occurring or syn~hetic su~skituted and unsubstitu~ed 3~ saturated and unsaturated, mixed or unmixed fatty acids hav-31 in~ about 14 to 30, e.g., 16 to 22, carbon ~toms per m~lecule.
32 Examples of such acld~ include stearic, hydro~y s~caric, such ~ ~ ~ 7 ~ ~

1 a~ 12~h~d oxy stear.,c, dihyd.roxy stearic, po~yhydroxy stearic 2 a~d other saturated hydrox~ fatty acid~, arachidic, oleic~
3 ricinole;.c, hydrogenat2d fish oil, tallow acids, etc ~ Intermediate molecular ~eight carbo~Jlic fatty

5 acids include those aliphatic, aromatic7 alkaryl7 etc.,

6 saturated, ~msubstitu~ed monocarboxyiic acids containing 7

7 to 12 carbcn atoJns per molecule9 e.g.~ capric~ lauric, capry-

8 lic, nonanoic, benzoic acid3 etc.

9 Low molecular weight fatty acids include saturated lo and unsatura~ced9 substitll~ed and unsu~s~itu~ed, aliphati~
11 carboxylic acids having about 1 ~o 6 carbon atoms. These 12 acids include at~y acids such as fo~nic9 acetic, propionic, 3 e~c. Ace~ic acid or its anhydride is preferred.
14 Metal bases which are.frequently used to neutralize 15 ~he above acids are the hydroxides, oxides, carbonates or 16 alcoholates o alkali metals (e~g. li~hi~n.and sodi~n~ or of 17 alkaiine earth me~als ~e.g.9 calciumj magnesium? strontium 8 and barium) or other polyvalent me~als commonly used in 19 grease making~ e.g. aluminum.
Yarious o~her additives may also be added ~o ~he 21 lubrica~ing c~nposi~lon ~e.g. 0,1 to 10.0 wt. percent based 22 on the ~otal weigh~ of the composi~ion~ for example, oxida-23 tion lnhibi~ors such as phenyl-alpha-naph~hylamine; tackiness 24 agents ~uch as polyisobutylene; st.abilizers such as aluminum 25 hydroxy stearate; and the like.
26 The lubricatin~ oil employed as such or to produce lub-27 r~cating grease compositlons ;.n the method of ~his invention 28 may be conventlonal natural oils as well as syn~hetic 29 lubricating oils, although the mineral lubricating oils are 30 pree~red, The synthe~.ic oils include synthet:ic~ lubricating 31 oils having a viscosity o~ at: leas~ 30 SSU at lOO~F. such as 32 ~ ers o~ monobasic acids (e,~. es~er of C~ Oxo alcohol ~it~h .. 7 ~

~7 1 C8 Oxo acid3 ester o C13 Oxo alrohol wi'ch octanoi~ acid, etc 2 es~ers of ~ibasic acids (e g d;-2 ech~l hexyl sebaca~e, di-3 no~yl adipate, etc.) esters of glycols (e.g. C13 O{o acid 4 diester o te~raethylene glycol, e~c.) complex esters (e g.
5 ~he complex es~er formed by reacting 1 mole of sebacic acid 6 with 2 moles of tetrae~llylene glycol and 2 moles of 2-ethyl 7 hexanoic acicl, comp1ex ester ~ormed by reac~ing 1 mole o tetra-8 ~thylene glycol with 2 moles of sebacic acid and 2 moles o~ 2-9~ethylhexanol, complex ester ~ormed by reacting together 1 mole o of azelaic acid, 1 mole of tetraethyl~ne ~lycol, 1 mole of C~
Oxo alcohol7 and 1 mole of C8 Oxo acid), es~ers o phosphoric 12 acid (e.g., the ester formed by contacting 3 moles of the mono-13~me~hyl ether of ethylene glycol with 1 mol~ of phosphorus oxychloride3 e~c ) 5 halocarbon oils (e.g. the polyme~ of ~chlorotrifluoroethylene containing 12 recurring units of chloro-6~trifluoroethylene~7 alkyl silica~es (e.g. methyl polysiloxanes9 17lle~hyl polysiloxanes, methyl phenyl polysiloxanes, e~hyl phenyl siloxanes~ etc.), sulfite esters (e.g. e~ter formed by 14 ~eacting 1 mole of sulfur ~xych~oride wlth 2 moles of the 20lmethyl ether of ethylene glycol, etc.), carbonates (e.~. tne 2llcarbonate fo~ned by reacting C8 Oxo alcohol with e~hyl carbo~
22jnate to form a half es~er and reactlng-this half ester with 23lte~raethylene glycol), me~captals (e.g , the mercap~al formed 24 by reac~ing 2-ethyl hexyl mercap~an wi~h formaldehyde~9 25 ~o~nals (e.g., the formal ~ormed by reac~ing C13 Oxo alcohol 26 with f~nmaldehyde~, polyglycol ~ype syn~hetic oils (e.g~ the 27 compounds formed ~y condensing butyl alcohol with ~ units of 28 propylene oxide, etc.), or m;xtu~es of any o~ the a~ove ln 29 any p~oportions. Quite generally the mineral ~ s~lthetic ~ oils should have a viscosity wi~hin ~he range of about 35 ~o 31 200 SSU at 210F and ~ash points of about 350 to 600~ F
32 Lu~ricating olls havlng a viscosi~y lndex of 100 or hi~her may be employed.
In the attached drawings:
Figure I shows a thermogravimetric trace for the oxidation of ZnPS3 and MoS2;
Figure II is a schematic view of a ball on cyliner testing device;
Figure III is a graph showing test results using "realistic" conditions;

Figure IV, IVA & IVB reproduces the surface profiles for several tests using a surface profilometer; and Figure V shows test results obtained using a journal bearing test device.
- TEST DATA
Typical MXY3 compositions were studied under differing conditions so as to define the limits of their applicability.
They were subjected to high temperatures under inert, oxidizing and reducing atmosphere and the point of deteri-oration (T min) was determined from thermal gravimetric experiments. X-ray analysis was used to identify the end product.
A. Thermal Decomposition ZnPS3 1000C~ Xo(-Zn5 + Y~ -ZnS + 1/4 P4S~ + 1/4 S~

(X + Y = 1) Tmin, = 450C

3 1000c FeS ~ 1/4 P4S7 ~ 1/4 S~
Tmin = 590 C

9 _ ~9~3~

B. Oxidation 3ZnPS3 + 31/2 2 1000C ~-zn3(po4)2 2 2 5 T i = 450C

FePS3 + 52 1000C FePO4 + 3S2 min. ~

MoS2 + 7/2 2 ) 3 2 Tmin. 310 C

C. Reduction 3 / 2 700C XO(-ZnS + Y~ -ZnS + 3H2S + PH
~ ' .
(x + y = 1) T . = 450C
mln .

3 7/2H2 1000C FeS + 3H2S~ + PH3 . 20 T i = 540C

.

_ 9~ _ ~1~3~'^f3'1F~

1 F~g1lre ~ or.Js th~ ~hermogravimGtric trace for t~e 2 o~.idation o~ 7~nP53 and MoS2. Repor~s in ~he li~erature 3 shcw a si~lificant increase in ~he co~icien~ o~ friction 4 ~or MoS2 a~ high ~e~mperatures which correla~es ~ith ~he on-5 set of oxida~lonO The increased stabili~y of ZnPS3 ~Tmin 6 C~..50C) and FePS3 (Tm~ - 4~ C) relative to MoS2 (Tmin=3lO~C) 7 under ~his realistî~ ~o~idizing) condition demons~rates their 8 superiority as a lubrican~ in real life situations.
9 In addi~iorl ~o the chemical s~abili~y o~ the MPS3

10 phases at eleva~ed temperatures9 their compatib~lity with

11 other che~icals has also been tes~edO Thege ma~erials are

12 stable to dissolution in E~2O9 ~S29 and hydrocarbons such as pen~ane, heptane~ cyclohexane, ben~ene9 ~ylene and toluene.
In addi~ion9 other organics such as methanQl, e~hanol, di-15 ethyl ether~ acetone and trichlorome~hane nei~her reac~ wi~h 16 nor dissolve ZnPS3 or FePS3. However9 ZnPS3 and FePS3 17 react wi~h strong aci.ds and bases (i,e. HCl9 HNO3~ CH3COOH, 8 KOH9 NaOH). The MPS3 phases also react with Lewis bases 19 such as a~non;.a and pyridine.
20 The s~ability of ~he MP53 phases in solven~s~ par- -21 ticularly hydrocarbons, is an importan~ feature necessary 22 ~or the synthesis o~ lubricating oil and ~rease dispersions ~3 and goes ~o enhan~e the des~rability of ~hese MXY~ compounds ~4 as additive~.
~5 Tes~s o ZnPS3 a~ a dry lubrican~ under various 26 conditions (atmosphere lnert or oxidizing and dry or moist;
27 slid~ng ~pe~d-5 to 50 cm~sec; and load ioo MPa to 750 MPa 28 Hertz Stress) have been conducted usin~ the ball-on-cylinder 29 deviee, ~ . Fig~re II is a schematic o~ ~he ball on.cylinder 31 device which consis~s bas1cal.ly o a s~ationary ball which 3~ ~s loaded onto a ro~a~ing cylinder-. A dead weight load is _ 1.0 . .

1~9731~ -1 applied to the end o~ a lever syst~m which in turn loads 2 the ball (5?100 s~eel 9 ~C 20 to 22) onto the cylinder 3 (52100 steel~ Rc 60 to 62) with a cal~ ~ble initial Hertz~
4 ian Stress, Through th~ use of a variable speed motor, the 5 cylinder can be rotated to obtain various sliding velocities, 6 The test device is equipped with a transducer ~or recording 7 ~he frictional force. ~dditional flexibility is available 8 by enclosing the device in a gas tight enclosure which 9 allsws various blanketing abmospheres ~o be inves~iga~ed, 10 The test lubrican~ was burnished onto a precleaned (50%
11 xylene/50 methanol) cylinder from a degreased lint-free 2 cloth which ~Jas loaded with excess material, The cloth

13 containing the lubricant was pressed onto the cylinder

14 under specified condi~ions of load rota~ion speed and time (200 g force9 200 RPMs and 15 min,~. In this way repro-16 ducible film s co uld be achieved, 17 Figure III shows ~ypical resul~s obtained using jB "realistic" condi~ions (moist air, 50 cm/sec sliding speed 19 and 500 MPa l~e~tz S~ress)~ The initial low fric~ion re~
corded or the nonlubricated case can be attributed to the 21 existence o an oxide surace film, The rapid increase and eventual ailure corresponds to a progressive removal o~ the surface oxide. Optical inves~igat~on o~ ~he wear surace a~er failure wi~h no solid lubricant reveals a everely galled area conflrming an adhe~ve ~ w~r mechanism.
The all of~ o the coeficien~ o friction for both MoS2 27 ~nd ~nPS3 in the ini~ial portion of the ~es~ is similar to 28 that observed o~ other lamell ar solid lubricants . This 29 "induction" or "run-inl' period can be a~tributed to an alignment of the crystallites on the wear surface. It ~s 31 clear rom this data that the friction reduction obtained ~3~ ~sing MoS2 îs be~ter than that ~ound ~ur ZnPS3. How~v~r, - 1~973~

1 the efect~ve lifetime o~ ~he MoS2 film is significantly 2 less than that observed for ZnPS3 burnishing.
3 In addition ~o recording ~he frictional characLer 4 and ef~ec~ive life9 an assessm~nt of the wear damage can be made using a surface p~ofllometerO Figure IV reprodu~es 6 the surace profiles for several tests. From cylinders 7 burnished wi~h ZnPS3 and run in ~he presence of a base oil 8 (Solvent 150~ ~ a signilcant reduction in wear can be no~ed 9 relative to ~he base oil case~ (Figure IVa). In addition9 comparison of wear traeks for areas burnished with ZnPS3 and 11 MoS~ respec~ively, w~lloh we~e terminated before failure9 12 also rev~als a signiiean~ reduc~ion in wear (Figure IVb).
13 Op~ical ex~nina~-on o ~he wear tracks genera~ed for ZnPS3 14 and MoS2 bu~nished areas confirm reduced wearO The MoS2 lubricated ~rack is severely galled and pi~ted. The ZnPS3 6 track is smooth and shows l~ttle or no evidence o galling.
17 In addltion to the ball on cylinder tests, the 18 ~ore common four ball test was also made. For these tests, 19 the precleaned 52100 ~eel balls were burnished by rolling in excess ~olid lubrican~ or 1 hour a~ 20 revolu~ions per 21 minu~e An evalua~ion of the wear was made by optically 22 measu~ing ~he wear scar diameter (WSD) genera~ed on the 23 ~hree s~ationar~ ba~s-24 Table I records ~he da~a for the cases of no , . .
lubricant7 ~nd for MoS2 and ZnPS3 trea~s. For bo~h MoS2 26 ~nd ZnPS3 a reduetion in wear rela~ive ~o an unlubrica~ed 21 case can be noted. For the lubrica~ed tests9 the presence 28 of an oxidizing a~mosphere degrades the antiwear activity.
29 A signi~ican~ increase in wear is observed in going from 30 iner~ to oxidizing a~mosphere for MoS2 treats. Similar 3I behavior is observed'for the ZnPS3 burnished areas~ however, 32 the ~ncrease in wear is much less ~han that found or MoS~

l ~rea~ed ballsO
2 ~gure V shows the results obtained using the 3 journal bear.ing test deviceO The application of ZnPS3~ by 4 burnishing on a runin journal9 resul~ed in reduc~ion of ~he riction coefficient~ The initial coeficient dropped 6 by 20% and ~hen slowly increased over a period of 25 days, 7 This particular ~est was conduc~ed in ~he presence of and in 8 con~unc~ion with a base oil and confi~med the initial wor~
9 done on the ball-on-cylinder device which showed a similar reduction o~ ~riction and ncreased anti-wear ac~ivity.

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_ 13 -~73~

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~1 7~}~8 l EYAMP~E I
2 4g of ZnPS3, FePS3 and MoS2 were added respective-3 ly to 9Gg of an aluminum complex soap-salt grease made from 4 the following components:
90 g Animal Fa~ty Acid 6 30 g Benzoic Acid 7 50 g Kolat:e (aluminum alcoholate, isopropyl) 8 1742 g Coray ~0/50 (unextracted naph~henic 9 mineral lu~ricating oil) 6 g UOP '~25 ~commercial anti-oxidant) ll The greasc was prepared by heating the mixture of acids and 12 alcoholate in the oil, w~th the removal of alcGhol, to form 13 ~he complex of the alumlnum with the fatty acid and benzoic l4 ~cid, and adding the anti-oxidant. The test materials, i.e.
t5 the ZnPS3, FePS3, and MoS2 were mixed respectively lnto the ~6 grease components at room temperature and the resulting formu-17 lations were milled so as to mix the solid component uniform1y 18 in the grease. In addition, two standard extreme pressure form~
19 ulations, base grease ~ 2% Elco 114 (zinc dialkyl dithiophosphat~
and base grease ~ 3% ~ric31cium phosphate ~ 1% sulfurized poly-21 butene were ormulated and milled. Each grease formulation was 22 subsequentl~ tested for extreme pressure properties follo~ing 23 the reapproved 1974 ASTM procedure for "Measurement of Extreme-24 pressure properties of lubricating greases (Four Ball Method)"
(Designation D 2596-69). For the base grease and for each ~6 formula';ion the wear scar diameter (mm) was measured as a 27 function of the applied load (l~g). The last non-seizure 28 load and the weld point were recorded and the standard loa~
29 wear index was calculated. Table Il shows the results for these tests.
, * Trade Marks

- 15 -~7~8 l ThRT~ r. r 2 RESULTS O~ FOUR ~ALL EXTR~ PRESSUR~
T~STS (AS~M D 259G-6~
3 Load Sample Descrlption ~lear Index 5 Base Grease ~0 6 Base Grease ~ 2~/o Elco 114 25 7 Base Grease ~ 3% Trtcalci~phosphate 33 8 1% Sulfuri~ed polybu~ene 9 Base Grease ~ 4% MoS~ 37 o Base Grease ~ 4a/O FePS3 39 ll Base Grease ~- 4% ZnPS3 44 12 From ~his data we see tha~ addi~ion o~ ZnPS3 or FePS3 13 to an aluminum complex soap grease ilr.pro~es the extreme 14 pressure characteristics relative to the base grease lS and also ~;th respect to standard ex~treme prcssure formu-

16 lations. In addition the perfonnance of the grease ~ith

17 4% ZnPS3 or FePS3 is superior to that found or a grease

18 fo~mula~ed with an cquivalent amount of the well-kno~m

19 solicl lubrican~ MoS2, .
X~MPlE Il 21 ZnPS3 was added,4%, 2C/o and 1% by weigh~,to an 22 aluminum complex soap grease prepared~as in Example I.
23 The resulting grease ormulations were milled ~o disperse 24 the so~id metal pbosphorous trisulfide thrvu~hout the grease matrix. Each o these ormulations along with the base grease 26 were evaIuated using the standard hSTM D ~596-69 and ASTM D
.
- ~ 27 2509-73 tes~ procedures. The lozd wear index and the Timken 28 pass desi.~nation given in Table III show the effectiveness of 29 ZnPS3 as an extreme pressure additive even ~I)en this material is present as a la/o ~y weight acldit~ve. These greases were not : ~ ~ 31 compounded witll finely divided particulates and are thlls very 32 crude test combinations.
s * Trade Mark " . - ' 7~

j TAP~7,E IIX
2 RESULTS OF EXTREI~E PRESSURE TEST FOP~ AN AL~.~INI~
COMPLEX SOAP GR ~SE-ZnPS~ GREASE FOR~ULATI~ S
3 Load Wear Tlmken Sample Desi~nat~on _ Index (Pass.lFail3 5 ~ase Grease 25.6 Not Tested 6 Base Grease -t 4% ZnPS3 47.6 . Pass 7 Base Grease ~ 2% ZnPS3 43.8 Fail 8 Base Grease ~ 1% ZnPS3 34.3 Pass EXAMPLE III
ZnPS3 was hand burnished on~o a 1.5 ~h di~meter ll steel cylinder (AISI 52100 Rc ~ 20 to 22). The cylinder 12 was plaeed on a shat which allowed it to rota~e creating 13 a 50 cmlsec tangential velocity relative to a fixed 1/2 inch 14 diameter steel ball (AISI 52100 Rc ~ 60 t~ 62) (see Figure II). The cylinder ro~a~ed in an oil (solvent 150 N mineral 16 oil) ~illed trough which constantly wet its surface with a 17 ~ilm o oil. The coeficient of dynamic friction between 18 the cylinder and the ball was recorded or the 30~nute duxa~ '~
19 tion of the tests. No signi~ican~ variation in the dynamic fric~ional coefficient (~D ranged from 0.10 to 0.12~ was 21 noted ~or the ~es~ run on the burnished area rela~ive to 22 the unburnished portion of the cylinder. ~owever~ a subse-23 quent investigation o ~he wQar s~ar profiles, Figure IV, 24 using a profilometer, showed a dramatic reduc~ion in wear for the ~s~ run on the burnished area rel~tive to ~he un~
26 burnlshed area.

: ~ , ' ' . I

' .
. - 17 -.: , , i

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of lubricating contacting surfaces at high temperatures and/or oxidizing conditions which comprises using, as a lubricant, material of the formula MXY3 wherein M is selected from the group consisting of Mg, V, Mn, Fe, Co, Ni, Zn, Cd, Sn, Pb and mixtures thereof, X is phosphorus, arsenic, antimony or mixtures thereof and Y is sulfur, selenium or mixtures thereof.

2. The method of claim 1 wherein X is phosphorus.

3. The method of claim 2 wherein Y is sulfur.

4. The method of claim 3 wherein the material is ZnPS3 or FePS3 or PbPS3.

5. The method of claim 4 in which said material is present as an additive in a lubricating oil or grease.

6. The method of claim 5 in which the lubricating grease comprises a thickener.

7. The method of claim 6 in which the thickener is a polyvalent metal salt of carboxylic acids.

8. The method of any one of claims 1, 4 or 5 wherein the high temperature at which lubrication is maintained is in the range of from about 310°C to about 450°C.

9. a lubricant comprising a major amount of lubricating oil and about 0.1 to 20 wt. % of material of the formula MXY3 wherein M is selected from the group con-sisting of Mg, V, Mn, Fe, Co, Ni, Zn, Cd, Sn, Pb and mix-tures thereof, X is phosphorus, arsenic, antimony or mix-tures thereof and Y is sulfur, selenium or mixtures thereof.

A lubricant according to claim 9, wherein said lubricant includes a grease thickener.

11. A lubricant according to claim 10, wherein said grease thickener is a polyvalent metal salt of carboxylic acids.

12. A lubricant according to claim 11, wherein said grease thickener is an aluminum complex of C14 to C30 fatty acid and benzoic acid.

13. A lubricant according to claim 9, wherein said lubricant is a fluid composition and said material of said formula is dispersed therein.

14. A lubricant according to claim 10 or 13, where-in said material is ZnPS3 or FePS3.